scholarly journals Growth rates of icicles

1994 ◽  
Vol 40 (135) ◽  
pp. 319-326 ◽  
Author(s):  
N. Maeno ◽  
L. Makkonen ◽  
K. Nishimura ◽  
K. Kosugi ◽  
T. Takahashi
Keyword(s):  
Growth Rate ◽  
Wind Speed ◽  
Water Supply ◽  
Growth Rates ◽  
Water Drop ◽  
Water Film ◽  
Freezing Process ◽  
Diameter Growth ◽  
Supply Rate ◽  
Measured Length

AbstractExperimental and theoretical studies on the growth rate of an icicle were carried out as a function of temperature, water-supply rate and wind speed; the relative humidity was also taken into account. The length of an icicle increases by the downward growth of thin dendritic crystals into the supercooled pendant water drop at the tip, and thus the growth is in the crystallographica-axis direction. The diameter, on the other hand, increases by the freezing of a water film flowing down along the icicle wall. The ratio of measured length-and diameter-growth rates was large, namely 8–32.Both growth rates increased with decreasing temperature and increasing wind speed. The increase in water-supply rate led to the decrease in the length-growth rate but no significant change in the diameter-growth rate. These results could be well described by a numerical model of icicle growth which takes account of the dendritic growth at the tip and the wall and the effective heat transfer within the turbulent boundary layer around the icicle. A formation mechanism of ribs and hollows is discussed in relation to the flowing and freezing process of water on an icicle wall.

scholarly journals Growth rates of icicles

1994 ◽  
Vol 40 (135) ◽  
pp. 319-326 ◽  
Author(s):  
N. Maeno ◽  
L. Makkonen ◽  
K. Nishimura ◽  
K. Kosugi ◽  
T. Takahashi
Keyword(s):  
Growth Rate ◽  
Wind Speed ◽  
Water Supply ◽  
Growth Rates ◽  
Water Drop ◽  
Water Film ◽  
Freezing Process ◽  
Diameter Growth ◽  
Supply Rate ◽  
Measured Length

AbstractExperimental and theoretical studies on the growth rate of an icicle were carried out as a function of temperature, water-supply rate and wind speed; the relative humidity was also taken into account. The length of an icicle increases by the downward growth of thin dendritic crystals into the supercooled pendant water drop at the tip, and thus the growth is in the crystallographic a-axis direction. The diameter, on the other hand, increases by the freezing of a water film flowing down along the icicle wall. The ratio of measured length-and diameter-growth rates was large, namely 8–32.Both growth rates increased with decreasing temperature and increasing wind speed. The increase in water-supply rate led to the decrease in the length-growth rate but no significant change in the diameter-growth rate. These results could be well described by a numerical model of icicle growth which takes account of the dendritic growth at the tip and the wall and the effective heat transfer within the turbulent boundary layer around the icicle. A formation mechanism of ribs and hollows is discussed in relation to the flowing and freezing process of water on an icicle wall.

scholarly journals Observation and Simulation Studies of Three Types of Wire Icing

Atmosphere ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 234 ◽  
Author(s):  
Tianshu Wang ◽  
Shengjie Niu ◽  
Jingjing Lv ◽  
Yue Zhou ◽  
Yuan Wang
Keyword(s):  
Growth Rate ◽  
Wind Speed ◽  
Growth Rates ◽  
Correlation Coefficients ◽  
Liquid Water Content ◽  
Jiangxi Province ◽  
Ice Thickness ◽  
Simulation Studies ◽  
Freezing Rain ◽  
Meteorological Elements

Research on three types of wire icing evolution mechanism is of great significance for ice disaster recognition and prediction. Comprehensive field observations of wire icing were conducted in the winters of 2015/2016 and 2016/2017 at the Lushan Mountain Meteorological Bureau Observatory (elevation 1164.5 m), Jiangxi Province, China, and the ice thickness, weather phenomena, meteorological elements, and fog spectrum were measured. Four icing cases were recorded, in which high ice-producing conditions, such as freezing rain, snow and supercooled fog, occurred. The icing growth and shedding mechanisms in three types of weather (freezing rain, snow, and supercooled fog) were analyzed and compared. Considering mixed ice-producing conditions, the ice thickness was simulated by integrating freezing rain, snow, and supercooled fog icing models, with inputs such as the precipitation rate and wind speed. The average measured icing growth rates in freezing rain, snow, and supercooled fog were 0.4, 0.3, and 0.2 mm h−1, respectively. The correlations between the icing growth rate and both the temperature and the wind speed were stronger in the snow and supercooled fog than in freezing rain. With the decreasing temperature, the icing growth rate increased faster with snow, while that in supercooled fog increased faster as the wind speed increased. In freezing rain, snow, and supercooled fog, the icing growth rates were all positively correlated with the ice thickness, with correlation coefficients of 0.55, 0.67, and 0.79, respectively. Ice was shed when the temperature remained below 0 °C, the wind speed fell to 2.7 m s−1, and the fog liquid water content fell to 0.036 g m−3 in supercooled fog, and when the solar radiation increased and the temperature exceeded 0 °C in freezing rain. The average sticking efficiency of the wire to snow was 0.03; its variation range was 0.01–0.10. The integrated model can simulate the changes in actual ice thickness well.

scholarly journals An evaluation of the effect of an angiotensin-converting enzyme inhibitor on the growth rate of small abdominal aortic aneurysms: a randomised placebo-controlled trial (AARDVARK)

2016 ◽  
Vol 20 (59) ◽  
pp. 1-180 ◽  
Author(s):  
Gaia Kiru ◽  
Colin Bicknell ◽  
Emanuela Falaschetti ◽  
Janet Powell ◽  
Neil Poulter ◽  
...  
Keyword(s):  
Growth Rate ◽  
Adverse Events ◽  
Angiotensin Converting Enzyme ◽  
Technology Assessment ◽  
Growth Rates ◽  
Controlled Trial ◽  
Health Technology ◽  
Diameter Growth ◽  
Converting Enzyme ◽  
Abdominal Aortic

BackgroundAlthough data are inconsistent, angiotensin-converting enzyme inhibitors (ACE-Is) have been associated with a reduced incidence of abdominal aortic aneurysm (AAA) rupture in analysis of administrative databases.Objectives(1) To investigate whether or not the ACE-I perindopril (Coversyl arginine, Servier) reduces small AAA growth rate and (2) to evaluate blood pressure (BP)-independent effects of perindopril on small AAA growth and to compare the repeatability of measurement of internal and external aneurysm diameters.DesignA three-arm, multicentre, single-blind, randomised placebo-controlled trial.SettingFourteen hospitals in England.ParticipantsMen or women aged ≥ 55 years with an AAA of 3.0–5.4 cm in diameter by internal or external measurement according to ultrasonography and who met the trial eligibility criteria.InterventionsPatients were randomised to receive 10 mg of perindopril arginine daily, 5 mg of the calcium channel blocker amlodipine daily or placebo daily.Main outcome measuresThe primary outcome was AAA diameter growth using external measurements in the longitudinal plane, which in-trial studies suggested was the preferred measure. Secondary outcome measures included AAA rupture, AAA repair, modelling of the time taken for the AAA to reach the threshold for intervention (5.5 cm) or referral for surgery, tolerance of study medication (measured by compliance, adverse events and quality of life) and a comparison of the repeatability of measures of internal and external AAA diameter. Patients were followed up every 3–6 months over 2 years.ResultsIn total, 227 patients were recruited and randomised into the three groups, which were generally well matched at baseline. Multilevel modelling was used to determine the maximum likelihood estimates for AAA diameter growth. No significant differences in the estimates of annual growth were apparent [1.68 (standard error 0.02) mm, 1.77 (0.02) mm and 1.81 (0.02) mm in the placebo, perindopril and amlodipine groups, respectively]. Similarly, no significant differences in the slopes of modelled growth over time were apparent between perindopril and placebo (p = 0.78) or between perindopril and amlodipine (p = 0.89). The results were essentially unaffected by adjustment for potential confounders. Compliance, measured by pill counts, was good throughout (> 80% at all visit time points). There were no significant in-trial safety concerns. Six patients withdrew because of adverse events attributed to the study medications (n = 2 perindopril,n = 4 amlodipine). No patients ruptured their AAA and 27 underwent elective surgery during the trial (n = 9 placebo,n = 10 perindopril,n = 8 amlodipine).ConclusionsWe were unable to demonstrate a significant impact of perindopril compared with placebo or amlodipine on small AAA growth over a 2-year period. Furthermore, there were no differences in the times to reach a diameter of 5.5 cm or undergo surgery among the three groups. Perindopril and amlodipine were well tolerated by this population. External AAA measurements were found to be more repeatable than internal measurements. The observed AAA growth measurement variability was greater than that expected pre trial. This, combined with slower than expected mean growth rates, resulted in our having limited power to detect small differences between growth rates and hence this adds uncertainty to the interpretation of the results. Several further analyses are planned including a multivariate analysis of determinants of AAA growth, an evaluation of the possible differential effect of perindopril on fast AAA growth and an investigation into the roles of central BP and BP variability on AAA growth.Trial registrationCurrent Controlled Trials ISRCTN51383267.FundingThis project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 20, No. 59. See the NIHR Journals Library website for further project information. The NIHR Biomedical Research Centre based at Imperial College NHS Trust supported the trial. Servier provided perindopril at no charge.

Frequent Irrigation Increases Growth of Pot-in-Pot Sugar and Red Maple

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 474
Author(s):  
Robert K. Witmer ◽  
Roger Harris ◽  
Alex X. Niemiera
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Sugar Maple ◽  
Stem Diameter ◽  
Production Cycle ◽  
Diameter Growth ◽  
Red Maple ◽  
Irrigation Regime ◽  
Moderate Growth ◽  
Stem Diameter Growth

In Virginia, pot-in-pot production of shade trees is normally accomplished by growing bareroot whips in 56-L containers for two complete growing seasons (production cycles). This study monitored the growth of Acer saccharum L. `Green Mountain' (sugar maple), a species with moderate growth rate, and Acer rubrum L. `Franksred' (red maple), a species with a fast growth rate, under standard once-a-day irrigation regime (1X) and a cyclic three-times-a-day regime (3X). Equal daily volumes of water were applied under each regime. Height growth rate increased for sugar maples but decreased for red maples in production cycle two compared to production cycle one. Stem diameter growth rates remained steady for red maple, but increased slightly for sugar maple. A 3X irrigation regime increased stem diameter of red maples, but had no other effect on either species in year one. Height and stem diameter growth of both species were increased by the 3X treatment during production cycle two. This study indicates that the standard production period results in decreased growth in the second production cycle for red maple, but not for sugar maple. Growth rates can be enhanced with a 3X irrigation regime for both species in production cycle two. The 3X irrigation regime only increases the stem diameter growth of red maple in the first production cycle.

Allometry, adult stature and regeneration requirement of 65 tree species on Barro Colorado Island, Panama

2006 ◽  
Vol 22 (2) ◽  
pp. 123-136 ◽  
Author(s):  
Stephanie Bohlman ◽  
Sean O'Brien
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Stand Structure ◽  
Community Level ◽  
Barro Colorado Island ◽  
Diameter Growth ◽  
Tree Allometry ◽  
Level Analysis ◽  
Canopy Species ◽  
Adult Stature

This study provides a community-level analysis of how regeneration requirement and adult stature are related to tree allometry (diameter, height and crown size) throughout post-seedling ontogeny on Barro Colorado Island, Panama. Comparing 65 species, gap species are taller, have higher diameter growth rates and occupy more low-canopy sites (≤10 m canopy height) than shade species at small diameters (≤10 cm dbh). For trees >10 cm dbh, diameter-height relationships and growth rates no longer differ between gap and shade species, but shade species have larger, particularly deeper, crowns than gap species. Species with tall adult stature have more slender stems with larger crowns compared with treelet and mid-canopy species starting at 5 cm dbh. From 10 to 40 cm dbh, diameter growth rate is also significantly greater for tall species. The consistent allometric differences between functional groups on a community level will, in part, determine vertical and horizontal stand structure.

scholarly journals Leaf:wood allometry and functional traits together explain substantial growth rate variation in rainforest trees

AoB Plants ◽  
2019 ◽  
Vol 11 (3) ◽  
Author(s):  
E F Gray ◽  
I J Wright ◽  
D S Falster ◽  
A S D Eller ◽  
C E R Lehmann ◽  
...  
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Functional Traits ◽  
Wood Density ◽  
Specific Leaf Area ◽  
Growth Rates ◽  
Cost Benefit ◽  
Diameter Growth ◽  
Rate Variation ◽  
Stem Diameter Growth

Abstract Plant growth rates drive ecosystem productivity and are a central element of plant ecological strategies. For seedlings grown under controlled conditions, a large literature has firmly identified the functional traits that drive interspecific variation in growth rate. For adult plants, the corresponding knowledge is surprisingly poorly understood. Until recently it was widely assumed that the key trait drivers would be the same (e.g. specific leaf area, or SLA), but an increasing number of papers has demonstrated this not to be the case, or not generally so. New theory has provided a prospective basis for understanding these discrepancies. Here we quantified relationships between stem diameter growth rates and functional traits of adult woody plants for 41 species in an Australian tropical rainforest. From various cost-benefit considerations, core predictions included that: (i) photosynthetic rate would be positively related to growth rate; (ii) SLA would be unrelated to growth rate (unlike in seedlings where it is positively related to growth); (iii) wood density would be negatively related to growth rate; and (iv) leaf mass:sapwood mass ratio (LM:SM) in branches (analogous to a benefit:cost ratio) would be positively related to growth rate. All our predictions found support, particularly those for LM:SM and wood density; photosynthetic rate was more weakly related to stem diameter growth rates. Specific leaf area was convincingly correlated to growth rate, in fact negatively. Together, SLA, wood density and LM:SM accounted for 52 % of variation in growth rate among these 41 species, with each trait contributing roughly similar explanatory power. That low SLA species can achieve faster growth rates than high SLA species was an unexpected result but, as it turns out, not without precedent, and easily understood via cost-benefit theory that considers whole-plant allocation to different tissue types. Branch-scale leaf:sapwood ratio holds promise as an easily measurable variable that may help to understand growth rate variation. Using cost-benefit approaches teamed with combinations of leaf, wood and allometric variables may provide a path towards a more complete understanding of growth rates under field conditions.

scholarly journals Growth pattern in tropical mangrove trees of Bunaken National Park, North Sulawesi, Indonesia

2019 ◽  
Vol 20 (6) ◽  
Author(s):  
RIGNOLDA DJAMALUDDIN
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growth Pattern ◽  
National Park ◽  
Stem Growth ◽  
Growth Patterns ◽  
Diameter Growth ◽  
North Sulawesi ◽  
Individual Trees ◽  
Mangrove Trees

Abstract. Djamaluddin R. 2019. Growth pattern in tropical mangrove trees of Bunaken National Park, North Sulawesi, Indonesia. Biodiversitas 20: 1713-1720. Seasonal diameter growth patterns in mangrove are often related to rainfall, temperature and moisture regime. At any localities, specific environmental factors may influence growth rate of individual trees. I asked whether stem growth of tropical mangrove in BNP is constant over a year, and whether stem growth rates are different by sites, species, and trees of the same species. Dendrometer bands were installed on trees from twelve different sites in BNP to measure stem growth rates. Measurements were made at two months intervals from July 1999 to June 2001 and March 2014 to December 2016. Growth rates measured in trees at the twelve sites varied significantly from 0.83 ± 0.27 to 1.71 ± 0.31 mm month-1. Growth rates were higher on Sonneratia alba (1.65 ± 0.69 mm month-1), low on Rhizophora stylosa, Xylocarpus moluccensis, Avicennia marina, Ceriops tagal (0.82 ± 0.16, 0.82 ± 0.18, 0.85 ± 0.18, 0.88 ± 0.28 mm month-1, respectively), and medium on Rhizophora apiculata, Bruguiera parviflora, Bruguiera gymnorrhiza, Rhizophora mucronata (1.19 ± 0.16, 1.22 ± 0.69, 1.25 ± 0.49, 1.31 ± 0.22 mm month-1, respectively). Statistically, growth rates were higher in trees with initial girths more than 50 cm compared to trees with initial girth less than 50 cm on B. gymnorrhiza, C. tagal, and R. mucronata, but these were slower for R. apiculata and S. alba. Between individual trees in six species tested, the differences in diameter growth rate were statistically significant. Growth rates varied among different site conditions, and the effect of soil water salinity on these was significant at higher intertidal sites. Growth rates exhibited seasonal patterns, and these were correlated positively with rainfall and negatively with temperature. The effect of the 2015-2016 El Nino was significant on reduced growth rates.  

scholarly journals Assessing mPTC Progression during Active Surveillance: Volume or Diameter Increase?

2021 ◽  
Vol 10 (18) ◽  
pp. 4068
Author(s):  
Maria Cristina Campopiano ◽  
Antonio Matrone ◽  
Teresa Rago ◽  
Maria Scutari ◽  
Alessandro Prete ◽  
...  
Keyword(s):  
Growth Rate ◽  
Active Surveillance ◽  
Growth Rates ◽  
Diameter Growth ◽  
Volume Increase ◽  
Node Metastases ◽  
The Mean ◽  
Definition Of ◽  
Immediate Surgery ◽  
Sensitive Marker

Active surveillance (AS) is considered an alternative to immediate surgery in micropapillary thyroid carcinoma (mPTC). However, the definition of clinical mPTC progression during AS is controversial. We evaluated changes in tumor size using both tumor diameters and volume in 109 patients with mPTC followed in an AS protocol for a mean period of 31 ± 18 months. At the time of data lock, 19/109 (17.4%) mPTC reached and maintained a volume increase of ≥50%. However, only 3/19 (15.7%) showed progression, according to the diameter increase. The remaining 16 showed a slight diameter growth without reaching the original protocol progression criteria. The mean mPTC growth rate in stable cases was 0.37 mm3/month, while it was significantly greater in the mPTC, which achieved a volume change ≥50% with respect to the other. The two mPTC that developed a significant diameter increase had a growth rate of 41 and 18 mm3/month. Instead, the growth rates of the three mPTC that developed lymph node metastases were 0, 2.5 and 16 mm3/month. The ≥50% volume increase appears to be a too sensitive marker of disease progression, with a downstream higher surgery rate. The assessment of growth rate could distinguish mPTC with high and low growth rates, which would allow us to tailor the algorithm of the evaluations to a more appropriate timing.

Comparison of copper sulphate pentahydrate growth rates determined by different methods

1990 ◽  
Vol 55 (7) ◽  
pp. 1691-1707 ◽  
Author(s):  
Miloslav Karel ◽  
Jiří Hostomský ◽  
Jaroslav Nývlt ◽  
Axel König
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Fluidized Bed ◽  
Growth Rates ◽  
Copper Sulphate ◽  
Crystal Growth Rate ◽  
Effect Of Temperature ◽  
Rotating Disc ◽  
Shape Factors ◽  
Data Treatment

Crystal growth rates of copper sulphate pentahydrate (CuSO4.5 H2O) determined by different authors and methods are compared. The methods included in this comparison are: (i) Measurement on a fixed crystal suspended in a streaming solution, (ii) measurement on a rotating disc, (iii) measurement in a fluidized bed, (iv) measurement in an agitated suspension. The comparison involves critical estimation of the supersaturation used in measurements, of shape factors used for data treatment and a correction for the effect of temperature. Conclusions are drawn for the choice of values to be specified when data of crystal growth rate measurements are published.

Measurement of growth rates for single crystals and pressed tablets of CuSO4.5 H2O on a rotating disc

1989 ◽  
Vol 54 (11) ◽  
pp. 2951-2961 ◽  
Author(s):  
Miloslav Karel ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Growth Rates ◽  
Diffusion Coefficients ◽  
Preferred Orientation ◽  
Rotating Disc ◽  
Dissolution Rates ◽  
Rates Of Growth ◽  
Good Agreement

Measured growth and dissolution rates of single crystals and tablets were used to calculate the overall linear rates of growth and dissolution of CuSO4.5 H2O crystals. The growth rate for the tablet is by 20% higher than that calculated for the single crystal. It has been concluded that this difference is due to a preferred orientation of crystal faces on the tablet surface. Calculated diffusion coefficients and thicknesses of the diffusion and hydrodynamic layers in the vicinity of the growing or dissolving crystal are in good agreement with published values.

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